Method for determining when to replace a filter having a pressure relief valve

0001The following patent application is a continuation of U.S. patent application Ser. No. 10/301,946, now U.S. Pat. No. 6,841,065, filed Nov. 22, 2002, which is a continuation of U.S. patent application Ser. No. 09/800,982, now U.S. Pat. No. 6,540,909, filed Mar. 7, 2001, which is a formalization of Provisional Patent Application Ser. No. 60/220,540, filed Jul. 25, 2000.

FIELD OF THE INVENTION

0002The present invention relates to fluid filters, and more particularly, a fluid filter having a pressure relief valve to provide an accurate visual indicator as to the remaining life of a filter element.

BACKGROUND OF THE INVENTION

0003It is well known to utilize fuel filter assemblies to filter fuel for a combustible engine of a motor vehicle. Such fuel filter assemblies comprise a variety of different orientations of the fuel filter assembly. For example, it is known to utilize sideways, downwardly, and upwardly mounted canisters having a paper filter media enclosed in the canister. With respect to upwardly mounted fuel assemblies, prior art filtration devices have been known to draw fuel into the filter assembly by use of a pump on the outlet side of the filter assembly. The fuel is directed downward into a lower chamber of the filter assembly wherein the fuel flow proceeds upward into an upper filter chamber of the filter assembly. The fuel may then be contained and sealed by a transparent filter cover or closure and a filter mount which may separate the lower chamber from the upper chamber.

0004Within the filter chamber of the filter assembly, the filter assembly may provide a filter canister comprised of a filter media circling a central filter tube that is contained by filter end caps at the top and bottom of the filter media. The end caps are sealed to the edges of the filter media to preclude any possible leak paths at the ends of the filter canister. The filter media typically comprises a porous paper material that may be pleated or concentrically wound so as to direct the fluid through the filter media. The filter media removes and retains undesirable contaminants within and on the media.

0005As fluid enters the filter chamber, the fuel level rises and passes through from the outside to the inside of the filter media. The fuel then flows downward into a central passage located along the central axis of the canister. The central passageway is in communication with a fuel outlet wherein the fuel passes outwardly from the filter assembly.

0006During the filtering process, the fuel is either drawn into the filter chamber by a vacuum or pushed into the filter chamber by pressure until the fuel finds a path through the filter media. As the fuel flows through the filter, dirt and other contaminants larger than the porous openings in the filter media, are trapped and retained by the filter media. These contaminants plug or clog the porous holes in the filter media and restrict or close the paths used by the flowing fuel. The fuel is then forced to seek other open and less restrictive flow openings which are available above the level of the fuel by climbing the height of the filter and accessing the clean areas of the filter media. This process of clogging and climbing continues until the filter media is completely immersed in the flowing fuel.

0007Even though the filter media may be completely immersed in the flowing fluid, the incoming fuel continues to pass through the filter media. It is not until the filter media becomes greatly clogged that the filter media needs to be replaced. This is a problem since the user generally views the height of the fuel in the filter chamber to see if the filter media is clogged. If the filter media is completely immersed in fuel, the user generally believes that the filter media needs to be replaced. Therefore, this type of system may lead to premature replacement of the filter media.

0008It would be desirable to provide a fuel filter assembly that provides an accurate indication as to the remaining usefulness of the filter media.

SUMMARY OF THE INVENTION

0009The present invention provides a fluid filter assembly that provides an accurate indication of the remaining usefulness of a filter element. The present invention provides a vertical, transparent housing having a fuel inlet for communicating fluid into the housing and a fluid outlet for communicating fluid downstream of said housing. A filter element is disposed within the housing between the fluid inlet and the fluid outlet for filtering the fluid. A means for maintaining and relieving a predetermined level of pressure across the filter element provides an accurate visual indicator as to whether the filter element needs replacement.

0010Preferably, the maintaining and relieving means provides a divider that is connected to the filter element and extends between a housing wall and an unfiltered side of the filter element. The divider divides the housing into an outer region and an inner region, wherein the outer and inner regions are in communication at a lower portion of the housing. A relief valve is in communication with a filtered side and the unfiltered side of the filter element and is located in the top of the filter element in the outer region of the housing. The relief valve opens when the pressure across the filter element exceeds the predetermined pressure level thereby raising the level of fluid in the outer region of the housing and indicating that the filter element needs replacement. A segment of filter media may be adjacently mounted to the relief valve to filter any unfiltered fluid that passes through the relief valve to the filtered side of the filter element.

0011Alternatively, the maintaining and relieving means may provide a restrictive filter media integrally connected to the filter element. The restrictive filter media prevents the flow of fluid through the restrictive filter media until the pressure across the filter element reaches the predetermined pressure level thereby causing the fluid in the housing to rise and indicating that the filter element needs replacement.

BRIEF DESCRIPTION OF THE DRAWINGS

0012The description herein makes reference to the accompanying drawings wherein like referenced numerals refer to like parts throughout several views and wherein:

0013<figref idref="DRAWINGS">FIG. 1</figref> is a schematic drawing showing the fluid flow path and the normal rising fluid path of a prior art fuel filter assembly.

0014<figref idref="DRAWINGS">FIG. 2</figref> is a schematic drawing showing the rising fluid level in the fluid filter assembly of the present invention.

0015<figref idref="DRAWINGS">FIG. 3</figref> is a schematic drawing showing a segment of filter media being utilized above a relief valve of the present invention.

0016<figref idref="DRAWINGS">FIG. 4</figref> is a schematic drawing showing a segment of filter media being utilized underneath the relief valve of the present invention.

0017<figref idref="DRAWINGS">FIG. 5</figref> is a schematic drawing of a hang down fluid filter assembly of the present invention.

0018<figref idref="DRAWINGS">FIG. 6</figref> is a schematic drawing showing a restrictive media being utilized as a relief valve in the fluid filter assembly of the present invention.

0019<figref idref="DRAWINGS">FIG. 7</figref> is a bottom view of the filter element of the present invention.

0020<figref idref="DRAWINGS">FIG. 8</figref> is a sectional view of the filter element of the present invention taken in the direction of arrows <b>9</b>—<b>9</b> in <figref idref="DRAWINGS">FIG. 8</figref>.

0021<figref idref="DRAWINGS">FIG. 9</figref> is an exploded view of the relief valve shown in the top of the filter element of the present invention.

0022<figref idref="DRAWINGS">FIG. 10</figref> is a sectioned perspective view of the relief valve shown in the top of the filter element of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

0023Referring to the drawings, the present invention will now be described in detail with reference to the preferred embodiment.

0024<figref idref="DRAWINGS">FIG. 2</figref> shows a fluid filter assembly <b>10</b> of the present invention in its preferred form. The fluid filter assembly <b>10</b> is best suited for filtering and processing diesel fuel, but the fluid filter assembly <b>10</b> may also be utilized with other fluids, such as gasoline, oil, water, antifreeze, etc. The fluid filter assembly <b>10</b> is mounted vertically upright and provides a closed housing <b>12</b>, a lower fluid storage chamber <b>16</b>, and an upper filter chamber <b>17</b>. A fluid inlet <b>14</b> is in communication with the lower fluid storage chamber <b>16</b>, which is in communication with the upper chamber <b>17</b> through a passageway <b>15</b>. A filter element <b>20</b> is housed within the upper chamber <b>17</b> of the housing <b>12</b> for filtering a fluid <b>19</b> to a fluid outlet <b>18</b>. The fluid inlet <b>14</b> delivers fluid <b>19</b> into the housing <b>12</b> so that the fluid <b>19</b> may pass through the filter element <b>20</b> and out the fluid outlet <b>18</b>. A relief valve <b>38</b> mounted in the top of the filter element <b>20</b> opens when the pressure level across the filter element <b>20</b> reaches a predetermined level. A relief valve filter <b>40</b> filters fluid <b>19</b> that passes through the relief valve <b>38</b>. Preferably, the relief valve filter <b>40</b> is mounted below the relief valve <b>38</b>, as shown in <figref idref="DRAWINGS">FIG. 4</figref>, but alternatively, the relief valve filter may be mounted above the relief valve <b>38</b>, as shown in <figref idref="DRAWINGS">FIG. 3</figref>.

0025To filter contaminants from the fluid <b>19</b>, the filter element <b>20</b> is fabricated from a pleated porous paper material. The filter element <b>20</b> encircles a central filter tube <b>22</b> and is contained by a top and bottom end cap <b>24</b>, <b>26</b>, respectively, as seen in FIGS. <b>2</b> and <b>7</b>–<b>11</b>. The top and bottom end caps, <b>24</b>, <b>26</b> are sealed to the edges of the filter element <b>20</b> to preclude any possible leak paths at the ends of the filter element <b>20</b>. A flexible seal <b>28</b> is provided on the bottom end cap <b>26</b> of the filter element <b>20</b> to create a seal between the central filter tube <b>22</b> and an inner core <b>43</b> of the filter element <b>20</b> and ensure that unfiltered fluid <b>19</b> does not leak into or escape through the fluid outlet <b>18</b>. The filter element <b>20</b> is preferably pleated or concentrically wound but may also be arranged in any of the ways known to one familiar with filtration construction so as to direct the fluid <b>19</b> through the filter element <b>20</b>. In addition, the filter element <b>20</b> may be fabricated from a hydrophobic filter material to filter out water from the fluid <b>19</b>.

0026The portion of the housing <b>12</b> between the filter element <b>20</b> and an outer wall <b>37</b> of the upper filter chamber <b>17</b> of the housing <b>12</b> is preferably divided by a substantially frusto-conical divider <b>30</b>. The divider <b>30</b> has a top portion <b>32</b> that is either integrally or sealingly connected to the top end cap <b>24</b> of the filter element <b>20</b>. The divider <b>30</b> also has a bottom portion <b>33</b> that extends downward toward the bottom of the filter element <b>20</b>, while also tapering or flaring outward away from the filter element <b>20</b>. It should be noted that the present invention is not limited to a frusto-conical divider <b>30</b>, but rather, the divider may also be substantially cylindrical wherein the bottom portion of the divider may extend downward substantially parallel to the filter element <b>20</b>. In both embodiments, the divider <b>30</b> essentially divides the upper chamber <b>17</b> of the housing <b>12</b> into an inner portion or region <b>34</b> and an outer portion or region <b>36</b>. The inner portion <b>34</b> is the space contained between the outside or unfiltered side of the filter element <b>20</b> and the inner surface of the divider <b>30</b>. The outer portion <b>36</b> is the space contained between the outer surface of the divider <b>30</b> and the inner surface of the outer wall <b>37</b> of the upper chamber <b>17</b> of the housing <b>12</b>. The inner and outer portions <b>34</b>, <b>36</b> remain in fluid communication at the bottom portion of the upper filter chamber <b>17</b> of the housing <b>12</b>.

0027In order to maintain and relieve the pressure in the upper chamber <b>17</b> of the housing <b>12</b>, a relief valve <b>38</b> is mounted in the top end cap <b>24</b> of the filter element <b>20</b>. The top end cap <b>24</b> is fabricated from a thin metallic material having a shape complementary to the top of the filter element <b>20</b>. The top end cap <b>24</b> has a substantially circular configuration with sidewalls <b>39</b> that extend downward from its periphery to sealingly connect to and cover the top of the filter element <b>20</b>. The top end cap <b>24</b> also has a centrally located recessed portion <b>41</b> which is received by and complementarily engages the inner core <b>43</b> of the filter element <b>20</b>.

0028The recessed portion <b>41</b> of the top end cap <b>24</b> is formed by two layers of thin metallic material. A first inner layer <b>45</b> is integrally connected to the sidewalls <b>39</b> and the portion of the top end cap <b>24</b> that extends over the top of the filter element <b>20</b>. A second outer layer of the recessed portion <b>41</b> is formed by a substantially cylindrical cup that is connected to and complementarily engages the inner layer <b>45</b> of the recessed portion <b>41</b>. The inner layer <b>45</b> of the recessed portion <b>41</b> has a raised portion <b>49</b> relative to the outer layer <b>47</b>. The outer layer <b>47</b> has four apertures <b>51</b> that extend therethrough and align directly under the raised portion <b>49</b> of the inner layer <b>45</b> of the recessed portion <b>41</b>. A sheet of filter media <b>53</b> lies between the inner layer <b>45</b> and the outer layer <b>47</b> of the recessed portion <b>41</b> so as to cover the four apertures <b>51</b> extending through the outer layer <b>47</b>.

0029The raised portion <b>49</b> of the inner layer <b>45</b> provides two apertures <b>55</b>, <b>57</b> extending therethrough. The larger of the two apertures <b>55</b> receives a flexible valve member <b>58</b> having an inverted mushroom-shaped configuration. The stem portion <b>59</b> of the mushroom-shaped, configuration is disposed within the larger aperture <b>55</b>. The head portion <b>61</b> of the flexible member <b>58</b> extends across the underside of the raised portion <b>49</b> of the inner layer <b>45</b> such that the head portion <b>61</b> of the flexible member <b>58</b> covers the smaller aperture <b>57</b>. The smaller aperture <b>57</b> acts as a port such that when the pressure level across the filter element <b>20</b> reaches a predetermined level, the head portion <b>61</b> of the flexible member <b>58</b> flexes away from the smaller aperture <b>57</b> thereby allowing fluid <b>19</b> and/or air/vapor from the unfiltered side of the filter element <b>20</b> to pass through the smaller aperture <b>57</b>. Fluid <b>19</b> will only pass through the smaller aperture <b>57</b> after all of the air/vapor has first passed through the smaller aperture <b>57</b>. The fluid <b>19</b> and/or air/vapor passes through the sheet of filter media <b>53</b> and through the four apertures <b>51</b> in the outer layer <b>47</b> of the recessed portion <b>41</b> to the filtered side of the filter element <b>20</b>. Although the patentable subject matter may be limited to a relief valve <b>38</b> having the structure defined above, Applicants consider the invention to include any relief valve <b>38</b> having a structure that provides for the release of fluid <b>19</b> and/or air/vapor at a predetermined pressure level.

0030The relief valve <b>38</b> is normally closed until the pressure level across the filter element <b>20</b> exceeds a predetermined level. When the relief valve <b>38</b> is closed, the air/vapor within the outer portion <b>36</b> of the housing <b>12</b> is trapped thereby forcing the fluid level in the outer portion <b>36</b> to be lower than the fluid level in the inner portion <b>34</b>. This occurs because as long as the filter element <b>20</b> is not clogged, air/vapor and fluid <b>19</b> within the inner portion <b>34</b> will pass through the filter element <b>20</b> at a pressure less than the pressure level in which the relief valve <b>38</b> is to open. Once the pressure across the filter element <b>20</b> exceeds the predetermined level due to the filter element being sufficiently clogged, the relief valve <b>38</b> opens and allows air/vapor and/or fluid <b>19</b> to pass from the outer portion <b>36</b> of the housing <b>12</b> to the inner core <b>43</b> of the filter element <b>20</b>.

0031In a secondary embodiment of the fluid filter assembly <b>10</b>′, a restrictive filter media section <b>42</b> of the filter media <b>20</b>′ is either integrally formed on the top of the filter media <b>20</b>′ or is attached to the upper portion of the filter media <b>20</b>′, as shown in <figref idref="DRAWINGS">FIG. 6</figref>. The restrictive section <b>42</b> of the filter media <b>20</b>′ acts in the same manner as the relief valve <b>38</b> and the relief valve filter <b>40</b> of the preferred embodiment, but the secondary embodiment does not require the divider <b>30</b>. The restrictive section <b>42</b> of the filter media <b>20</b>′ only allows air/vapor and/or fluid <b>19</b> to pass through the restrictive section <b>42</b> once the pressure level across the filter element <b>20</b> exceeds a predetermined level. This ensures that the fluid level within the housing <b>12</b> will remain at a level below the restrictive filter media <b>42</b>. Once the predetermined pressure level is reached, air/vapor and/or fluid is allowed to pass through the restrictive filter media <b>42</b> thereby raising the fluid level and providing a visual indicator that the filter element <b>20</b>′ needs replacement.

0032In yet another embodiment of the present invention, a divider <b>30</b>″ and a relief valve <b>38</b>″ may be utilized in conjunction with a hang down fluid filter assembly <b>10</b>″, as shown in <figref idref="DRAWINGS">FIG. 5</figref>. The structure in this embodiment is similar to that of the preferred embodiment in that the divider <b>30</b>″ is sealingly connected to a top end cap <b>24</b>″. The divider <b>30</b>″ extends downward along the bottom portion of the filter element <b>20</b> while flaring outward from the filter element <b>20</b>. A relief valve filter (although not shown in <figref idref="DRAWINGS">FIG. 5</figref> but similar to that shown in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>) is mounted in a portion of the central filter tube <b>22</b>. The relief valve filter is incorporated with the relief valve <b>38</b>″ to prevent any unfiltered fluid <b>19</b> from entering fluid outlet <b>18</b>″. The relief valve <b>38</b>″ in the hang down fluid filter assembly <b>10</b>″ works in the same manner as the preferred embodiment. The divider <b>30</b>″ forms an outer portion <b>34</b>″ and an inner portion <b>32</b>″ of the housing <b>12</b>″ wherein the trapped air in the outer portion <b>34</b>″ forces the fluid level in the outer portion <b>34</b>″ to be lower than the fluid level in the inner portion <b>32</b>″. This allows the filter element <b>20</b> to become completely clogged before reaching the predetermined pressure level that will open the relief valve <b>38</b>″. Once the relief valve <b>38</b>″ opens, air/vapor passes through the relief valve <b>38</b>″ thereby allowing the fluid level in the outer portion <b>34</b>″ to rise and provide a visual indicator that the filter element <b>20</b> needs replacement.

0033In operation, the prior art device functions as depicted in <figref idref="DRAWINGS">FIG. 1</figref>. Fluid <b>19</b> enters the fluid inlet <b>14</b> of the fluid filter assembly <b>10</b> and accumulates within the lower chamber <b>16</b> of the housing <b>12</b>. Fluid flows through the passageway <b>15</b> leading to the upper filter chamber <b>17</b> wherein an unfiltered fluid level is established within the upper filter chamber <b>17</b>. The fluid <b>19</b> is drawn into the filter chamber <b>17</b> by vacuum (as most commonly occurs in diesel fuel filters) or forced by low pressure (as seen in oil, antifreeze or many other filters) until it finds a path through the filter element <b>20</b>. As the filter element <b>20</b> becomes partially clogged, the restriction increases temporarily overcoming the surface tension of fluid covering the unused pores of the filter <b>20</b> element and causing a temporary flow of air/vapor through the filter element <b>20</b>. As the air/vapor passes, it creates a void on the outside of the filter element <b>20</b>, and the fluid level rises to fill the void. The new fluid level allows flow through clean and unused pores of the filter element <b>20</b>, and the restriction through the filter element <b>20</b> reestablishes itself at a fluid level as previously described. Once the fluid level establishes itself, the surface tension of the fluid <b>19</b> across the remaining pores of the filter media <b>20</b> prevents the flow of air/vapor through the filter element <b>20</b> until, once again, the restriction increases to a level in which air/vapor is forced through the filter element <b>20</b>. This process continues as dirt and other contaminants in the fluid <b>19</b>, larger than the openings in the filter element <b>20</b>, are trapped and retained by the filter element <b>20</b> as the fluid <b>19</b> passes through the filter element <b>20</b>. These contaminants plug or clog the holes in the filter media <b>20</b> and restrict and/or close the paths used by the flowing fluid <b>19</b>. The fluid <b>19</b> is forced to seek other open and less restrictive fluid openings that are above the level of the fluid <b>19</b>, and therefore, the fluid <b>19</b> climbs up the height of the filter element <b>20</b> and uses the clean areas of the filter element <b>20</b>. The process of clogging and climbing continues until the filter element <b>20</b> is completely immersed in the flowing fluid <b>19</b>. When the fluid level reaches the top of the upper filter chamber <b>17</b>, this has generally been a visible indication to the user to change the filter element <b>20</b>. The problem with changing the filter element <b>20</b> at this point is that the filter element <b>20</b> still allows for the passage of fluid <b>19</b> through the filter element <b>20</b> even when the fluid level has risen to the top of the filter chamber <b>17</b>. Therefore, if the filter element <b>20</b> is changed immediately upon the fluid level rising to the top of the filter chamber <b>17</b>, then the filter element <b>20</b> is being replaced prematurely.

0034During the operation of the preferred embodiment of the present invention, fluid <b>19</b> enters the fluid filter assembly <b>10</b> and the upper filter chamber <b>17</b> in the same way as described in the prior art. However, by employing the divider <b>30</b> and incorporating the preset relief valve <b>38</b> in the top end cap <b>24</b>, the fluid level can be made to rise approximately in proportion to the plugging rate of the fuel element <b>20</b>. This gives an accurate visual indicator as to the remaining life of the filter element <b>20</b>. In so doing, the incoming fluid <b>19</b> and air/vapor initially behave as similarly described in the prior art. When the fluid level approaches the bottom of the divider <b>30</b>, the fluid <b>19</b> continues to rise between the filter element <b>20</b> and the inside surface of the divider <b>30</b>, which was previously defined as the inner portion of the housing <b>12</b>, but the fluid <b>19</b> does not rise between the outer surface of the divider <b>30</b> and the outer wall of the housing <b>12</b>, which was previously defined as the outer portion of the housing <b>12</b>. This is because the trapped air/vapor in the outer portion <b>36</b> of the housing <b>12</b> prevents the rise of fluid <b>19</b> into the outer portion of the housing <b>12</b>.

0035As to the inner portion <b>34</b> of the housing <b>12</b>, fluid <b>19</b> and air/vapor move through the filter element <b>20</b> in a usual manner. The fluid level continues to rise between the filter element <b>20</b> and the inside surface of the divider <b>30</b> as the filter element <b>20</b> becomes more clogged. This continues until the fluid <b>19</b> has risen to the full or nearly full height of the filter element <b>20</b>, as previously described. Once the filter element <b>20</b> is completely saturated, the pressure differential across the filter element <b>20</b> begins to increase with the increased clogging of the filter element <b>20</b>. Once this pressure differential reaches a predetermined level, preferably 5″ Hg, the relief valve <b>38</b> may open, and vapor/air may flow through the relief valve <b>38</b> while fluid flows through the filter element <b>20</b> since both present the same amount of resistance to flow. As the pressure differential across the filter media <b>22</b> begins to exceed the 5″ Hg point, the relief valve <b>38</b> becomes the preferred flow path since its pressure differential is fixed at 5″ Hg. Since air/vapor is closest to the relief valve <b>38</b>, the air/vapor flows through the relief valve <b>38</b> first, and the fluid <b>19</b> follows. The fluid level begins to rise in the outer portion <b>36</b> of the housing <b>12</b>, thereby providing a visual indicator to the operator that the filter element <b>22</b> is plugged. The relief valve filter <b>40</b> provided in the fluid path of the relief valve <b>38</b> ensures that the fluid <b>19</b> that passes through the relief valve <b>38</b> is filtered. Once the user sees that the fluid level in the outer portion <b>36</b> of the housing <b>12</b> has risen to the top of the upper filter chamber <b>17</b>, the user knows to replace the filter element <b>20</b>.

0036In operation, the secondary embodiment, as depicted in <figref idref="DRAWINGS">FIG. 4</figref>, works in a similar manner as described in the preferred embodiment. The fluid level rises within the filter chamber <b>17</b>, until it reaches the restrictive filter media <b>42</b> on the filter media <b>20</b>. When the fluid level reaches the restrictive media <b>42</b>, the pressure differential across the filter media <b>20</b>′ must rise to a preferred level of 5″ Hg in order for the air/vapor and fluid <b>19</b> to pass through the restrictive media <b>42</b>. The fluid level stops at a point just below the restrictive media <b>42</b> until the filter media <b>20</b>′ becomes so clogged that the pressure differential reaches the 5″ Hg level. At that point, air/vapor and fluid <b>19</b> pass through the restrictive media <b>42</b>, thus allowing the fluid level to rise within the filter chamber <b>17</b> of the fluid filter assembly <b>10</b>′. The user may then use the risen fluid level as an indicator that the filter media <b>20</b>′ needs to be replaced.

0037In operation, the alternative embodiment depicted in <figref idref="DRAWINGS">FIG. 5</figref> works in exactly the same manner as described in the preferred embodiment. The only difference in the embodiment depicted in <figref idref="DRAWINGS">FIG. 5</figref> is that the housing <b>12</b>″ is upside down, but the fluid level responds in the same manner as described in the preferred embodiment.

0038While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, the scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.